Re: OT: Re: FLASH: sound recording?

[John Croteau]

Hi John,


> > I've been trying to record some home-made sounds/effects for use in a

> > FLASH movie in ".wav" format.  For this purpose I have been using a

> > (cheap) microphone and the standard win-95 recording software.  This

> > has been giving me very noisy results (lots of background noise)

> > - Could someone please tell me if this is a problem with the microphone?

Probably, it is likely the wrong type (see below).


> > - If it is then is there any "noise-cancellation"

> > software/shareware out there which would mitigate the

> > effect of background noise in the recording?

Don't introduce noise in the first place, if possible.

Fixing noise problems are almost always difficult.


> Sorry John.  The problem is most likely not with your software, but with a

> combination of your mic and sound card.  Garbage In, Garbage Out (GIGO)

> unfortunately.  There is also the issue of where you are recording.  If you

> are in a noisy room (heaters, refrigerators, etc.), that will probably

> "read" in your recording.  My best guess is that the mic is the largest

> contributor to your problem.  Recording is a hobby of mine, so I could talk

> all day about it, but here are a few pointers that may help you out:


> 1) Start with a good mic.  This depends on your application, but an all

> around workhorse microphone that sounds decent with most stuff is a Shure

> SM57.  The SM58 is better suited to vocals.  Both pickup in a hypercardiod

> fashion (that means in a 'heart' shape with the most sensitive things being

> 'read' at the front of the mic), and reject noise from behind the head.

> They are not very expensive, and are quality 'instruments.'  $80 to $120 or

> so depending on where you are.  Avoid cheaper mics.  You do get what you

> pay for.  Shures are used the world over, especially for live

> applications.  If you look closely on MTV, The Tonight Show, David

> Letterman, etc, watch the bands and look at what they are using.  Lots of

> SM57s and 58s usually.  If you really want rich sound, you'll need to look

> at condenser mics which tend to be more expensive.

Actually using a cheap or expensive microphone is secondary to getting

the correct one. It is important to get a microphone that matches the

characteristics of the audio card or amp it is connected to. It is very

likely that the microphone you are using is high impedance and your

audio card is low impedance. If you use an extension cord use a good

one; a poor ground will introduce noise; better microphones use balanced

(3 pin XLR) connections and cable to cancel the introduction of external

noise. If you move the cable and noise increases or decreases you have a

problem that needs to be fixed.


Sound blaster cards have an impedance of 600 ohms with a suggested

signal level input range of 10-200mVpp. This is a low impedance

microphone. A common cause of excessive noise is a bad impedance match

between the microphone and the amp (sound card). If you use a high

impedance microphone whether it is cheap or expensive it is going to be

noisy when plugged into a low impedance input (and vice versa). Shure

SM-57 and SM-58 microphones are 150 ohms and only a fair match for Sound

Blasters.


> 2) You'll need a mic cable and some way to translate the mic signal to your

> sound card.  I go into a Mackie mixing board, and out to my Turtle Beach

> soundcard with a 'Y' cable RCA to 1/8".  You can probably find a used

> Mackie 1202 mixing board for around $200.  Mackie also makes good stuff

> that a lot of folks use.

Using a good preamp or mixer will give you much better performance and

flexibility than using a microphone connected to the mic input of most

sound cards directly (even if the mixer is a Mackie).

For an evaluation of a SoundBlaster card see:

http://www.hut.fi/Misc/Electronics/docs/soundcardtest/sb16value.html

To se noise of some cards see

http://members.xoom.com/nightsector/myra/noise.htm

Notice except for Mic the Sound Blaster Live cards are very quiet.

G3 amd iMac are very very quiet at least as shown on this page.


> 3) Use a good room.  Turn off or isolate electrical things that make subtle

> buzzes and hums.  Hang blankets and towels in the room to absorb sound

> reflections.  Experiment with mic position to find the right one.


> 4) Set a good level and don't overdrive your software inputs.  Watch the

> meters (if there are any), and get as close to '0' as possible without

> going over.  Sound Forge is a great piece of software, but I hear a lot of

> people love Cool Edit as it is shareware and it can do most of the same

> things.


> 5) Use a good sound card.  SoundBlasters have gotten better, but I will

> never buy one again after I've heard the accuracy of the Turtle Beaches.

> For an idea as to how noisy your card is, record without any output from

> your mixing board into your sound card (but leave everything still plugged

> in like normal). Look at the resulting waveform.  That is the noise floor

> of your sound card.  I did this test with my SB 16 and my Turtle Beach

> Tropez Plus, and there was a significant difference.  The Sound Blaster was

> much noisier than the Turtle Beach.  If you have an OEM SoundBlaster

> compatible knockoff card, chances are you have a noise machine in your

> computer.

The slot and position of the sound card and other cards in a computer

can create large differences in the base noise that a sound card has.

Make sure the case is on securely (unless you get less noise with it

off) . Also make sure your fans are quiet. The sound card will not pick

up the actual sound from noisy fans but an electromagnetic noise can be

transmitted through the air and/or the ground plane to the sound card

creating noise in the audio.


-----------                               -----------------------

John Croteau

croteauerols [dot] com (mailto:croteauerols [dot] com)

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